1. Field of the Invention
The present invention relates to a paint circulation system; and, more specifically, to a paint circulation system including a coiled back pressure regulator.
2. Description of Related Art
Modern manufacturing processes, including those used for automotive vehicles, typically utilize a paint circulation system capable of delivering a multitude of paint colors at the same time. Each color requires a separate distribution system including a network of supply and return lines, a plurality of paint applicators, such as spray guns or rotary bells and a circulation pump that operates to continuously circulate the paint within the system. The system also includes a back pressure regulator that operates to control pressure and fluid flow through the circulation system. Manual and automatic paint applicators require controlled fluid pressure and flow to efficiently and repeatedly apply paint to products such as automotive vehicles. Depending upon the type of paint used, current pressure regulation systems can be effective and efficient at controlling fluid pressure and flow. Typically, these regulators operate by changing velocity of the fluid by passing it through an orifice to the size of which is changed by tightening a valve member or gate to close the size of the opening or tightening a member to increase or decrease the size of a bladder and thereby restrict fluid flow. Such regulators, however, produce a large amount of paint shear as the continuous flow of paint is taken from a high pressure to a low pressure in a very short distance.
As color is a very important characteristic to the customer, particularly in the area of automotive vehicles, providing a large range of colors has become very important. One drawback of increasing available colors is that there is a lower percentage of demand on the other colors. Accordingly, reduced color usage correspondingly increases paint residence time in the circulation system. The longer the paint remains circulating in the current systems, the more paint shear occurs. Shear degradation is most apparent in short circulation systems local to the booths that are designed to offer special order or low-volume colors. Back pressure regulators in short systems typically operate under a high pressure drop in order to provide sufficient pressures at the paint applicators. Pigments and mica flakes in metal paints will deform or degrade over time when subjected to shear stress resulting in a less consistent paint appearance and the potential for increased replenishment of paint and scrap paint.
Accordingly, there is a need for a low shear back pressure regulator for use with a paint circulation system that reduces paint shear and corresponding paint degradation thereby resulting in a more uniform paint and less scrap.